T-Mobile announces Data Stash, allowing unused data to roll over

T-Mobile has announced a data-rollover initiative for customers. (John MacDougall / AFP/Getty Images)

T-Mobile on Tuesday announced a move aimed at combating one of the biggest frustrations of being a wireless customer.

With Data Stash, customers will be allowed to roll over their unused data with no cap on how much data can be accrued, Chief Executive John Legere said.

"What you don't use, you don't lose," Legere said during a live interview that was streamed on the carrier's website. The initiative, he said, is "screamingly obvious."

Eligible customers will be enrolled in the program automatically, Legere said. To kick things off, T-Mobile is also throwing in 10GB of free data.

As soon as the 10GB of free data is used up, a customer will begin to build his or her own Data Stash, automatically carrying over 100% of unused 4G LTE data, rounded up to the nearest megabyte, each month. That data is available for use for up to 12 months from when it is rolled.

Data Stash is the latest "Uncarrier" move rolled out by the nation's No. 4 wireless carrier as it aims to take on industry giants Verizon and AT&T.

T-Mobile has been aggressively rolling out various programs designed to shake up the industry, including payment of contract termination fees for people who switch to T-Mobile, free Wi-Fi calling and the practice of not counting music streaming against a customer's data bucket.

Asked during the interview whether price cuts and more liberal contracts will squeeze profits, Legere avoided a a direct answer but said T-Mobile is leaner than its rivals and can absorb the costs. During a call with reporters later, Chief Marketing Officer Mike Sievert said the move "involves some risk and there's a big investment on our part," but said that ultimately, "the math works very well for us."